WASHINGTON—Google Inc.’s chairman, Eric Schmidt, will testify before the Senate antitrust subcommittee in September to answer questions about the company’s growing dominance of the Internet.

Google had been reluctant to have Mr. Schmidt or other senior executives testify at a time when the Internet search giant is confronting a broad array of investigations into its business practices. But last month, senators on the panel warned they would use their subpoena power to compel one to appear.

On Friday, Sen. Herb Kohl (D-Wisc.), chairman of the subcommittee, announced that the company had complied with their demand.